To many, that would be a relief. Although some superdelegates said just a few weeks ago they'd welcome a deciding role, a backlash has been building to the notion that party insiders could tip the outcome. Superdelegates, known in the party rules as unpledged delegates, clearly are feeling the heat.

"There is an anger among a substantial element of the party who feel these unpledged delegates are somehow undemocratic, and if the primary result is overturned, the results are somehow illegitimate," says Stuart Rothenberg, an independent political analyst in Washington. "This is a major problem for the Democrats."

Early on, Senator Clinton amassed a big lead among superdelegates – a group that includes Democratic members of Congress and governors, Democratic National Committee officials, and 76 at-large delegates yet to be selected. In all, the superdelegates account for about one-fifth of delegates at the Democratic National Convention in August.

But a string of primary and caucus wins by Senator Obama shifted the momentum of the race – and left many congressional lawmakers and governors who had made early endorsements looking out of sync with their constituents.

Out of sync with voters at home

As of Tuesday, 242 superdelegates have endorsed Clinton and 160 have picked Obama, according to the Associated Press. Among superdelegates who hold elective office and whose states have already held primaries or caucuses, 92 have made public commitments that are at odds with the vote in their states. Here's the breakdown: 21 elected superdelegates back Clinton although their states or districts voted for Obama; 14 back Obama in states that went for Clinton. Another 33 elected superdelegates are uncommitted, although their constituents voted for Obama; 24 are neutral whose constituents voted for Clinton, according to the AP review.

"Our nominee must be chosen by Democratic voters, not by backroom deals of the party elite," says Charles Chamberlain, political director for Democracy for America, which launched a petition drive last Wednesday calling on superdelegates to respect the popular vote. So far, some 55,000 activists have endorsed the Internet petition.

Many superdelegates say they're already getting the message that respecting the popular vote is becoming an expectation.

"I'm not comfortable with the idea that we know better. I will vote as a superdelegate for Hillary Clinton, if she ends up with the most pledged delegates," says Sen. Claire McCaskill (D) of Missouri, who has endorsed Obama. "I'm confident that in my party, which prides itself as being a party of the people, superdelegates will be nominating the one with the most pledged delegates."

Rep. Eleanor Holmes Norton (D) of the District of Columbia had expected to wait until the August convention to make an endorsement. But the growing backlash to an outsized role for superdelegates prompted her to speak out in favor of the candidate supported by her district. She came out for Obama on the eve of the Feb. 12 D.C. primary, fully expecting that he would win.

"As a superdelegate, I decided I had to speak up now to separate myself from the idea ... that superdelegates, especially those who have not announced their choice, could or should decide our nominee under some circumstances," she said in a statement Feb. 11.

After '72, the rise of superdelegates

The category of superdelegate was first proposed after Democratic presidential nominee George McGovern was routed in the 1972 general election. The idea was that by playing a role in the nominating conventions, party professionals would help ensure that the nominee was electable – and would be supported by the party establishment in the general election.

"One of the things we're seeing this year – more than at any time since 1984 – is that some of the superdelegates are making a judgment based not just on who will make the best candidate, but decide to go along with the majority view in their district or state," says Anthony Corrado, professor of government at Colby College in Waterville, Maine.

Not since the 1984 nominating race between Vice President Walter Mondale and Sen. Gary Hart of Colorado has a Democratic primary been so contested. Mr. Mondale mounted an intense campaign for superdelegate votes, which put him over the top at the convention.

Most superdelegates interviewed for this story say they never expected that their role could be crucial this year.

"The role is to reflect a combination of factors: One is certainly the sentiment ... of my constituents in Rhode Island.... You also have to step back and make a judgment about the qualities of candidates and also the ultimate objective, which is to win the White House," says Sen. Jack Reed (D) of Rhode Island. "Those factors all come into play. I don't think there's a simple on/off switch: You either do what the primary voters tell you to do or you totally divorce yourself from that," he adds. "The objective is to win in November, not just help conclude the primary season. You've also got to help bring the party together."

Other superdelegates say there's too much fear among voters that they could wind up "stealing the election."

"Superdelegates play an important role because it's such a close campaign, but they were created for precisely the situation we may be in: to break a dead tie," says Elaine Kamarck at the Kennedy School of Government at Harvard University. A member of the Democratic National Committee, she is an at-large superdelegate and is pledged to Clinton. [Editor's note: The original version misspelled Ms. Kamarck's name.]

"They're not going to turn aside the will of the voters, unless there is some compelling reason to do that," she says. "Unless some scandal erupts or something strange happens, you can pretty much anticipate that the superdelegates will take into consideration the will of the voters."